Island



UNrrnnernaasrarnNr marron.

` MAn'rrNvr, DARLING, or rRovIDENoE, RHODE` ISLAND.

` smnnvanvn MOTION or STEAM-ENGINES; i

spe;raceteam` of rttxersratenf No. 11,246, dated July 11,y 1854'.

ZbfaZZ whom t concern .i lBe it known that I, MARTIN XMB.. DAR- LING, of the city and county of Providence and State of Rhode` Island, have invented a new and usefullimprovement in Slide-Valve` Motions of Steam-Engines, to make` the valvercut` ott', thefsteam at various points inthe` strokewas may bedesired; and` I ,do hereby `declare that` the following is a `full,

moving the valve to open thesteam ports,

and the latter to close them, whereby 'the `ports are opened and closed with `sufficient rapidity to enable the steam to be admitted full on the piston, and cut off at any point between about one fourth, or even less, of

` the stroke of the piston, `and the `end of said stroke.

To enable those skilled in theart to make and use my invention, I `will proceed to describe its construction and operation.

A, is the steam cylinder, which `is represented with a separate exhaust port for each steam port,- and fitted with two Valves, a, a, but this is not essential to myginvention, as it is well understood that the operation 4of the single short slide is the same as that of the two valves, as represented.

` b, is the way shaft, carrying the arm, c, to which the valve rod is attached, and the Zywith which connects the rod, le, from `a yoke, f, j, which surrounds the cam, g,

0n the crank shaft, z'. This cam` is of such l form, and so arranged upon the shaft, that it will give the proper length of stroke to `the valve for opening first one, and then the other of the steam ports, and that it will open the ports wide very early in the stroke of the piston. It fits to the yoke in such a way, that very soon after it has `passed the position at which it arrives to open the port wide, it will allow the yoke to receive such a movement independently of it, as would cause the valve to close the port. At the side oi'l the `calmly, isplaced `the eccentric, 7L,

5 which is made capable, of giving about twice i the-.amount-of motion given by the` cam, g, in` order thatlit may be capable of, giving l the valve` a.` vquicker motion. than the` cam.`

; rllhe eccentricfrod,I j,.which receives the rino,-`

tion `of the eccentric, .has` aneeye, Z2, rigidly l attached tofitsend, and this eye is of such.

`size internally. as. teebe capable of, sliding `freely on the yoke rod e, or of allowing the side rod to slide freely through it,and ithe yokerod,` e, is furnished with two xed stops ortappetpieces, Z, Z1 one oneach4 side of the eye, lc, to" control theslidingmotion `of the eye and the rod.,the` one `upon or `within the other.` The eccentric requires toi counter motion is used as represented, the

eccentric requires to be in a `position diametrically opposite to those described, as an illustration of which see the drawing where the steam is intended to be cut olf just after half stroke, and the eccentric is set a little less than halt a revolution in advance of the crank. The distance between the stops, Z, Z, on the yoke rod should be equal to the length of motion given by the eccentric, Zz., plus the depth of the eye, Ze, and the position of the stops on `the yoke rod will depend `upon the length of the eccentric rod, which may be about half that of the yoke rod.

The operation of the cam and eccentric on the valve can be best explained by reference to the drawing, where the directionof the revolution of the crank and the motion ot the piston, are indicated by arrows, the cam has nearly arrived on its center and the steam port, n, is nearly wide open. The yoke rod is now moving in the direction of the arrow, 5, but the eccentric rod is: moving in the opposite direction, as indicated by the arrow, O. As soon as the cam arrives on its center, the port will be full open, and will remain so as the cam continues its movement, owing to the shape of `the cam not heilig such as to return the yoke rod atv once. The eccentric, as it continues moving' in the same direction, will bring the eye, c, in contact with the stop, Z', and move the rod, e, along withit, until, by the time the eccentric is on its center, the valve has moved back far enough to close the port, n. It will be understood, that a similar action takes place during the movement of the piston in the opposite direction, the eccentric always leaving the kvalve or valves in proper position to be operated upon by the cam when it comes around.

I, by no means, confine myself to the employment of an eccentric'to close the valve, as a cam would effect the desired recult; but I merely use the eccentric, for the reason that it works and wears more smoothly and evenly than a cam and yoke, and I only use the cam to open the valve for the sake of opening the port fully, very early in the pistons stroke. i

What I claim as my lnvention, and desire to secure by Letters Patent, is

1. Combining the cam and yoke motion for opening the steam port, and the eccentric or cam and yoke motion for closingthe steam port, and causing the two motions to act on the valve, by connecting/with the valve the yoke rod, e, of the cam and yoke motion which gives the movement for opening the port, yand furnishing the rod, y', of the eccentric or cam motion which gives the movement for closing the valve, withv an eye, 7c, or its equivalent-,which plays between two stops or tappet pieces, Z, Z', properly arranged on the rod, e, substantially as described.

2. Giving to the eccentric, h, -or cam, which gives the movement to close the valve a greater throw than the cam, which opens the valve, in order that, at the proper time, the valve may be made to close the steam port and cut of the steam very quickly, or by a very small part of 'the revolution of ifzhe main shaft, as herein substantially set orth. f

MARTIN v. B. DmiLINGr. l

Witnesses DANIEL WIGHTMAN, LYoURGUs SAYLEs. 

